Want to Live Forever?

by Lifeboat Foundation Scientific Advisory Board member David Brin, Ph.D.

Looking for the fountain of youth

Recent scientific results have fired hopes for a
dramatic increase in human life span.

For more than a decade, studies suggested an approach
to slowing the ageing timer. The method that appeared
to work best has been to keep experimental subjects
hungry. By providing nutritious but restricted diets,
or in some cases by delaying sexual reproduction,
researchers as much as doubled longevity in rodents,
yeast, flies and several other species. As you’ve
expect, human enthusiasts began eagerly applying this
at home  limiting their caloric intake or else
forbearing sex  hoping to extend their own years
through judicious abstinence. It may seem a hard
tradeoff, abjuring some of life’s pleasures in
exchange for more years. But some think it
worthwhile.

According to a report in the November 23, 2002
edition of the journal Science, such tradeoffs may not
be necessary, after all.
Stewart Frankel of Yale
University reported that an enzyme  Rpd3 histone
deacetylase  may be key. Flies with genetic
mutations that resulted in lower levels of the enzyme
lived 33% to 50% longer than normal, emulating the
results of reduced caloric intake. “If you decrease
the level of the enzyme without eating less, you still
get the life span extension”, Frankel told Reuters.
Eager companies hope to find drugs that might emulate
these results in humans.

It sounds terrific  more high quality life span,
while eating whatever you like. What a deal!

Unfortunately, it may not be so easy.

First, some perspective. Do all animal species have
built-in expiration timers? Some fish and reptiles
may not, but mammals seem to have an inner clock that
goes off after an individual passes his or her species
“middle age” triggering a gradual descent toward
frailty, then death.

Mice and elephants lead very different lifestyles 
one ponderous, the other manic  yet rodents and
pachyderms share the same pervasive pattern of aging.
Individuals who survive the perils of daily life, from
disease to predators, inevitably begin declining after
finishing about half a billion heartbeats. Elephants
live much longer than mice, but their hearts also beat
far slower, so the total allotment stays remarkably
similar. Few mammals live to celebrate their billionth
pulse.

No one yet knows what this coincidence signifies.
Moreover, the program isn’t rigid. As we’ve seen,
researchers have used hunger to double the senescence
timer in mice. Unfortunately, humans who try caloric
restriction find no similar benefit. Beyond a slight
increase in vigor and some reduction in heart disease,
results have been disappointingly slim.

This should come as no surprise. Across time, many
civilizations fostered ascetic movements, in
monasteries and colonies where dedicated individuals
lived spartan, abstemious lives. After four millennia
of these experiments, wouldn’t we notice swarms of
spry, 200-year old monks capering across the
countryside? There may be ample reasons why such
simple measures work in animals, but not us.

Remember that billion heartbeat limit that seems to
confine all mammals, from shrews to giraffes? It’s a
pretty neat correlation, till you ponder the chief
exception.

Us. Most mammals our size and weight are already
fading by age twenty, when humans are just hitting
their stride. By eighty, we’ve had about three
billion heartbeats! Quite a bonus. How did we get
lucky?

Mice and elephants only get 1 billion heartbeats. David
Brin gets 3
billion.

Biologists figure our evolving ancestors needed
drastically extended lifespans, once humans came to
rely on learning rather than instinct to create
adaptable, tool-using societies. Two decades weren’t
enough for a man or woman to amass expertise, or pass
complex culture to new generations. We had to live
longer. Chimps and other apes share some of this
lifespan bonus, getting about half as many extra
heartbeats. So the adjustment must have begun millions
of years ago.

Evolution has already slowed human ageing. In
becoming mammalian Methuselahs, we’ve probably
incorporated all the easy stuff, including the
chemical effects that researchers recently stimulated
in mice, through caloric restriction.

I’d rather lose this bet! I’m more hungry for years
than fatty foods. But alas, it seems that little more
longevity will be achieved by simple asceticism, or by
pharmaceutically simulating drastic life style
adjustments. Good diet and exercise may help more of
us get our programmed eighty or ninety years. But to
gain a lot more  the same doubling that we see in
hungry mice  we’ll have to work harder. It may
require deciphering every part of life’s blueprint, a
project taking generations.

Disappointed? Well, be grateful for the triple
heartbeat bonus you already get. And work for the
next generation. They have always been the true
immortality.